Explains the mysteries of sound recording on film.


This movie is part of the collection: Prelinger Archives

Producer: Encyclopaedia Britannica Films
Sponsor: N/A
Audio/Visual: Sd, B&W
Keywords: Perception: Sound; Motion pictures: Sound; Motion pictures: Projection

Creative Commons license: Public Domain

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Reviewer: Green Xenon - - April 14, 2007
Subject: Analog Optical Audio in films
Hi:

I like using variable-density analog B&W monoaural negative [no positive and no "reversal"; just the negatives] film optical tracks for audio. The audio characteristics of the film make my mouth-water. Yes, for some wierd reason, the film's audio makes me hungry.

Why didn't they make an audio-only equivalent of this for music [i.e. an optical audio tape]?

Why not replace *Analog Magnetic Audio Tapes* with *Analog Optical Audio Tapes*??

Analog optical audio is used in films and sound better than analog magnetic audio.

Magnetic tape contains static, humming, and other electromagnetic disruptions whereas optical tape does not.

Optical tape is resistant to bar magnets whereas magnetic tape is not.

Analog optical audio records and plays in the same manner as film does.

The difference for me, is, I'd like to use only the negative film and no positive.


Regards,

Green Xenon

Reviewer: Spuzz - - June 11, 2005
Subject: Sounds like a nerd.. looks like one too!
Another dry EB film, with some interesting touches. This time, it's talking about how film is transferred on to motion pictures. While some of it is interesting, it mostly isn't. The things that got me were the voice of all those EB films finally having a face and the ending, but other than that, if you're not a techie nut wondering how film works, it's a snooze-through.

Reviewer: op712 - - January 6, 2003
Subject: Sound reproduction
Excellent presentation of the soundtrack on the 35mm film, and is similar with the soundtrack on the 16mm film as well. Later on, we added another track to the variable area to give out more dynamics and help reduce noise. The variable density had more noise since the light beam was continually going through a grey area even though there was no variable sound information. Then we came out with Dolby Stereo, version "A" -taking the two variable areas and giving them each a sound record to correspond to the left and right channels. Center channel was when left and right had the same information and the processor took this information as a mono record. Excellent history from the Britannica collection.

Shotlist

HOW MICROPHONE TRANSFORMS KINETIC ENERGY OF AIR WAVES INTO ELECTRICAL ENERGY; HOW FLUCTUATIONS IN ELECTRIC CURRENT OPERATE PHOTOGRAPHIC LIGHT VALVE WHICH REGISTERS THEIR FLUCTUATIONS THRU VARYING LIGHT BEAM UPON SENSITIZED PHOTOGRAPHIC FILM; REVERSE. VARIABLE AREA & VARIABLE DENSITY SOUND TRACKS EXPLAINED & DEMONSTRATED. SOUND FILM PROJECTORS. Best scenes: 1) The narrator actually speaking the soundtrack to the film in real time, and 2) the end, where you can "see" a soundtrack.

06:42:11:00 - 06:43:05:00
VS man transferring motion-picture film from one reel to another; CU individual frames on film picturing woman, arrow pointing to her; arrow points to optical soundtrack on film; picture negative and sound negative side-by-side; diagram showing how negatives combine to create positive

06:43:05:00 - 06:47:23:00
VS man sitting at desk, talking into microphone (this is James A. Brill, the narrator for all of the ERPI Classroom Films, speaking); animated sound waves emitting from man's mouth to microphone; CU sound waves going into microphone; VS diagraming how sound moves from microphone to amplifier to recorder and onto sound track strip; VS diagramming various kinds of sound track strips and how light passes through; VS diagramming sound from amplifier to loudspeaker

06:47:24:00 - 06:50:39:00
Diagram of parts of light valve: ribbons, light slot, bridges, tensioning means; CU man looking through microscope; diagram of light valve ribbons (as seen through microscope); VS diagram of lens, apertures and ribbon slots, lens system and film; VS parts of light valve

06:50:39:00 - 06:51:03:00
MCU balding man with glasses, sitting behind desk talking toward microphone

06:51:03:00 - 06:52:26:00
Diagram what different types of soundtracks (variable density and varible area) look like as they run




MICROPHONES SOUND WAVES ELECTRICAL ENERGY ELECTRIC CURRENT PHOTOGRAPHIC LIGHT VALVES SOUND RECORDING & REPRODUCTION Sound Sound recording Soundtracks Electronics Audio Physics Animation Science Microphones Film (animated) Soundtracks (animated) Announcers Narrators Speaking
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